• Bulletin of the Korean Chemical Society
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• 제32권11호
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• pp.3963-3966
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• 2011

A series of pyranopyrazoles, was efficiently synthesized via one-pot, four component reaction of ethyl acetoacetate, hydrazine hydrate, aldehydes and malononitrile in the presence of catalytic amount silicotungstic acid under solvent free condition. NOE experiments confirmed that the product exist exclusively in the 2H form. The present protocol offers the advantages of clean reaction, short reaction time, high yield, easy purification and economic availability of the catalyst.

• Archives of Pharmacal Research
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• 제12권3호
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• pp.201-206
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• 1989

The reaction of acetoacetanilide (1) with the $\alpha$-cyanocinnamonitrile derivatives 2 yielded the Michael adducts 4 which could be converted into the pyrano [2, 3, -c] pyrazole derivatives 5 via their reaction with hydrazine hydrate. Cyclisation of 4 afforded the derivatives 10. The pyranopyrazoles 9 reacted with different activated nitrile derivatives (3a-c) to give the pyrano [2, 3-c] pyridine derivatives 13. 16 and 19 respectively. The biological activity of the synthesised heterocyclic derivatives was investigated and discussed.

• Archives of Pharmacal Research
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• 제17권4호
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• pp.278-280
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• 1994

1,5-diketones(3) undewent cyclization to 4H-pyrano[3,2-d]pyrazoles (4a-d),4H-piperidino[3, 2-d]pyrazole (5) and pyrazolo[5,4-d]thiopyran (6) upon treatment with P/sub 2/O/sub 5/, CH/sub 3/COONH/sub 4/ and /or P/sub 2/S/sub 5/. Moreover, treatment of (4) with CH/sub 3/COONH/sub 4/ and/or P/sub 2/S/sub 5/ afforded (5) and (6). The structures of the hitherto unknown ring systems have been confirmed by analytical and spectral data.